Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2000-12-22
2003-10-21
Szekely, Peter (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C524S127000, C524S140000, C524S141000, C524S145000, C524S147000, C524S417000, C524S439000
Reexamination Certificate
active
06635698
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to flame retardant thermoplastic molding compositions.
BACKGROUND OF THE INVENTION
Polycarbonate sheet shows good performance and receives high ratings in several European fire tests, especially those for building and construction applications. The NF-P-92-507 norm for France divides sheet into 4 classes (M1 to M4) based on their burning behavior in the main test with electric heater or epiradiateur test (NF-P-92-501) and, if necessary, the flame propagation test (NF-P-92-504) and the melting or dripping test (NF-P-92-505). The classification of materials is determined by flame height(s), flame ignition time, total burning time (all in epiradiateur test), after flame time (flame propagation test) and dripping of burning particles (melting test).
For polycarbonate based sheet the classification is usually determined by the results obtained in the dripping test. Polycarbonate sheets of several design types and thickness may have M4 ratings due to the performance in the dripping test because burning particles may ignite the underlying cotton. Hence, it is desirable to enhance the performance of polycarbonate sheets to a more desirable rating of M1 or M2.
Typical commercial grades of polycarbonate sheets are made from linear or branched polycarbonate resin having a Melt Volume Rate (MVR) of about 5 cm
3
/10 min (300° C./1.2 kg), measured according ISO1133. It has been found that the pass rate of polycarbonate in the dripping test (NF-P-92-505) can be improved by lowering the viscosity of the polycarbonate material (see, for example, International Publication No. WO 00/26287). However, as a consequence the impact performance of the sheet will be lowered.
U.S. Pat. No. 5,942,585 to Scott et al relates to clear blends of polycarbonates and polyesters where the polyester comprises a dicarboxylic acid component based on 1,4-cyclohexanedicarboxylic acid units and a glycol component comprising 2,2,4,4-tetramethyl-1,3-cyclobutanediol units. Miscible polycarbonate polyester blends are described in a Free Volume approach to the Mechanical Behaviour of Miscible Polycarbonate Blends, by A. J. Hill et al, J. PHYS.: Condens Matter, 8, 3811-3827 (1996) and in Dynamic Mechanical and Dielectric Relaxation Study of Aliphatic Polyester Based Blends by Stack et al., J. M. Polym. Mater. Sci. Eng. (1993), 69, 4-5, Eastman Chemical Company, Kingsport, Tenn. 37662. These references focus on the transparent properties of the miscible blends.
Because of use of polycarbonate for forming transparent/translucent sheet material used in building and construction, enhancements to the flame retardancy of the material is desirable.
SUMMARY OF THE INVENTION
Addition of poly(cyclohexane dimethanol cyclohexane dicarboxylate) (PCCD) to polycarbonate (PC) results in an improved performance in the dripping test. The two polymers are completely miscible and mixing results in transparent translucent blends, having a single T
g
and excellent impact performance. The polycarbonate/poly(cyclohexane dimethanol cyclohexane dicarboxylate) (PCCD) compositions having a specific Melt Volume rate (MVR) have a higher pass rate in the dripping test than comparable polycarbonate compositions (with a similar MVR) that do not contain PCCD.
A transparent/translucent molding composition with improved flame redardancy comprising a uniform blend of a miscible resin blend of a polycarbonate resin and a cycloaliphatic polyester resin. The cycloaliphatic polyester resin comprising the reaction product of an aliphatic C
2
-C
20
diol or chemical equivalent and a C
6
-C
20
aliphatic diacid or chemical equivalent. The cycloaliphatic polyester resin contains at least about 80% by weight of cycloaliphatic components wherein the composition has at least a 80% pass rate in 10 test specimen in the Norme Francaise NF-P-92-505 flammability test of L'Association Francaise de Normalisation using test specimens with density between about to 1.0 about 6.0 kilograms per square meter.
In general, preferred polyester molecules are derived from cycloaliphatic diol and cycloaliphatic diacid compounds, specifically polycyclohexane dimethanol cyclohexyl dicarboxylate (PCCD). The polyester having only one cyclic unit may also be useful.
DETAILED DESCRIPTION OF THE INVENTION
The most preferred materials are blends where the polyester has both cycloaliphatic diacid and cycloaliphatic diol components specifically polycyclohexane dimethanol cyclohexyl dicarboxylate (PCCD). The preferred polycarbonate comprises units of bisphenol-A-polycarbonate (BPA), 6,6′-dihdyroxy-3,3,3′,3′-tetramethyl-1,1′-spiro(bis)indane (SBI), aryl substituted bisphenols, cycloaliphatic bisphenols and mixtures thereof.
The ratio of polycarbonate to cycloaliphatic polyester is desirable from about 75:25 to 99:1 by weight, more preferable from about 90:10 to 99:1 by weight, most preferable from 95:5 to 98:2 by weight of the entire mixture.
The cycloaliphatic polyester resin comprises a polyester having repeating units of the formula I:
where at least one R or R1 is a cycloalkyl containing radical.
The polyester is a condensation product where R is the residue of an aryl, alkane or cycloalkane containing diol having 6 to 20 carbon atoms or chemical equivalent thereof, and R1 is the decarboxylated residue derived from an aryl, aliphatic or cycloalkane containing diacid of 6 to 20 carbon atoms or chemical equivalent thereof with the proviso that at least one R or R1 is cycloaliphatic. Preferred polyesters of the invention will have both R and R1 cycloaliphatic.
The present cycloaliphatic polyesters are condensation products of aliphatic diacids, or chemical equivalents and aliphatic diols, or chemical equivalents. The present cycloaliphatic polyesters may be formed from mixtures of aliphatic diacids and aliphatic diols but must contain at least 50 mole % of cyclic diacid and/or cyclic diol components, the remainder, if any, being linear aliphatic diacids and/or diols. The cyclic components are necessary to impart good rigidity to the polyester and to allow the formation of transparent/translucent blends due to favorable interaction with the polycarbonate resin.
The polyester resins are typically obtained through the condensation or ester interchange polymerization of the diol or diol equivalent component with the diacid or diacid chemical equivalent component.
R and R1 are preferably cycloalkyl radicals independently selected from the following formula:
The preferred cycloaliphatic radical R1 is derived from the 1,4-cyclohexyl diacids and most preferably greater than 70 mole % thereof in the form of the trans isomer. The preferred cycloaliphatic radical R is derived from the 1,4-cyclohexyl primary diols such as 1,4-cyclohexyl dimethanol, most preferably more than 70 mole % thereof in the form of the trans isomer.
Other diols useful in the preparation of the polyester resins of the present invention are straight chain, branched, or cycloaliphatic alkane diols and may contain from 2 to 12 carbon atoms. Examples of such diols include but are not limited to ethylene glycol; propylene glycol, i.e., 1,2- and 1,3-propylene glycol; 2,2-dimethyl-1,3-propane diol; 2-ethyl, 2-methyl, 1,3-propane diol; 1,3- and 1,5-pentane diol; dipropylene glycol; 2-methyl-1,5-pentane diol; 1,6-hexane diol; dimethanol decalin, dimethanol bicyclo octane; 1,4-cyclohexane dimethanol and particularly its cis- and trans-isomers; 2,2,4,4-tetramethyl-1,3-cyclobutanediol (TMCBD), triethylene glycol; 1,10-decane diol; and mixtures of any of the foregoing. Preferably a cycloaliphatic diol or chemical equivalent thereof and particularly 1,4-cyclohexane dimethanol or its chemical equivalents are used as the diol component.
Chemical equivalents to the diols include esters, such as dialkylesters, diaryl esters and the like.
The diacids useful in the preparation of the aliphatic polyester resins of the present invention preferably are cycloaliphatic diacids. This is meant to include carboxylic acids having two carboxyl groups each of which is attached to a saturated
de Moor Johannes Jacobus M.
Goossens Johannes Martinus D.
Hoogland Gabrie
van der Heijden Walter C. M.
Verhoogt Hendrik
General Electric Company
Szekely Peter
LandOfFree
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